Fair Value (Details)	1 Months Ended	12 Months Ended			24 Months Ended
	May 31, 2016 USD ($)	Dec. 31, 2016 USD ($) derivative venture	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) derivative
Derivative instruments and Hedging Activities
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months		$ (6,975,000)
Income (loss) on cash flow hedges		(5,556,000)	$ 5,354,000	$ (121,000)
Payments for Hedge, Financing Activities		$ 14,847,000	$ 0	$ 0
Cash Flow Hedges Interest Rate Caps
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative		11			11
Puts
Derivative instruments and Hedging Activities
Number of ventures in which entity is required to purchase interest in investment at guaranteed minimum amount | venture		3
Interest Rate Caps | Cash Flow Hedges Interest Rate Caps
Derivative instruments and Hedging Activities
Notional balance		$ 35,898,000			$ 35,898,000
Weighted average interest rate (as a percent)		2.70%			2.70%
Weighted average capped interest rate (as a percent)		5.90%			5.90%
Interest Rate Swap [Member] | Cash Flow Hedges Interest Rate Caps
Derivative instruments and Hedging Activities
Notional balance		$ 800,000,000			$ 800,000,000
Weighted average capped interest rate (as a percent)		2.30%			2.30%
Derivative, Notional Amounts Entered into During Period					$ 1,200,000,000
Derivative, Notional Amounts Settled During Period	$ 400,000,000
Non-designated Hedges Interest Rate Caps
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative		15			15
Non-designated Hedges Interest Rate Caps | Interest Rate Caps
Derivative instruments and Hedging Activities
Notional balance		$ 715,820,000			$ 715,820,000
Weighted average interest rate (as a percent)		2.50%			2.50%
Weighted average capped interest rate (as a percent)		6.20%			6.20%